I am not an expert on power but as long as it will provide enough power to run the machine and charge the battery at the same time I think we will benefit a lot from that since it will in time be easier to find replacement power cords and such.

USB-C power is a bit of a kludge. The specs say 100W, but the pins in the connector will wear out if the user hotplugs the power while charging. And I can see most users doing just that: close laptop, pull plug.

USB-C is a bit of a mixed bag, I'm afraid. There is everything on that one connector, even analog audio. Great care needs to be taken in designing power circuits if you want the analog audio to sound good. And since people will also want to charge their laptop over USB-C, that seems like a hell of a job.

I think we will be seeing a lot of budget laptops with features that are not implemented at all, or working not so good over USB-C.

I would like at least 2 standard USB2 ports. Not USB-C, nor USB3.

If you run Linux or BSD and would like to use an external audio interface, your choice is limited to USB Class Compliant devices. None of those work over USB3 or USB-C.

There will also be no new audio interfaces with USB-3 or USB-C as that market is going to Thunderbolt or ethernetAVB. There are a couple of USB-3 interfaces available (most notably from Zoom), but these don't work with Linux or BSD at all.

USB3 is mostly backwards compatible with USB2. Not with USB 1.1 for audio. It might work, but will break up and/or crackle on most hardware. And the same goes for USB-C. It's backwards compatible with USB3, but further down the line, ymmv.

This is not a problem for harddisks, as copying files isn't a synchronous process. Recording or playing audio is a synchronous process, meaning, you can't delay it for too long, or the sound drops or crackles. And the same goes for video digitizers and USB connected GPU's.